bool SimpSMTSolver::asymm(Var v, Clause& c) { assert(decisionLevel() == 0); if (c.mark() || satisfied(c)) return true; trail_lim.push(trail.size()); Lit l = lit_Undef; for (int i = 0; i < c.size(); i++) if (var(c[i]) != v && value(c[i]) != l_False) { uncheckedEnqueue(~c[i]); } else l = c[i]; if (propagate() != NULL){ cancelUntil(0); asymm_lits++; if (!strengthenClause(c, l)) return false; }else cancelUntil(0); return true; }
// Backward subsumption + backward subsumption resolution bool SimpSolver::backwardSubsumptionCheck(bool verbose) { int cnt = 0; int subsumed = 0; int deleted_literals = 0; assert(decisionLevel() == 0); while (subsumption_queue.size() > 0 || bwdsub_assigns < trail.size()){ // Check top-level assignments by creating a dummy clause and placing it in the queue: if (subsumption_queue.size() == 0 && bwdsub_assigns < trail.size()){ Lit l = trail[bwdsub_assigns++]; (*bwdsub_tmpunit)[0] = l; bwdsub_tmpunit->calcAbstraction(); assert(bwdsub_tmpunit->mark() == 0); subsumption_queue.insert(bwdsub_tmpunit); } Clause& c = *subsumption_queue.peek(); subsumption_queue.pop(); if (c.mark()) continue; if (verbose && verbosity >= 2 && cnt++ % 1000 == 0) reportf("subsumption left: %10d (%10d subsumed, %10d deleted literals)\r", subsumption_queue.size(), subsumed, deleted_literals); assert(c.size() > 1 || value(c[0]) == l_True); // Unit-clauses should have been propagated before this point. // Find best variable to scan: Var best = var(c[0]); for (int i = 1; i < c.size(); i++) if (occurs[var(c[i])].size() < occurs[best].size()) best = var(c[i]); // Search all candidates: vec<Clause*>& _cs = getOccurs(best); Clause** cs = (Clause**)_cs; for (int j = 0; j < _cs.size(); j++) if (c.mark()) break; else if (!cs[j]->mark() && cs[j] != &c){ Lit l = c.subsumes(*cs[j]); if (l == lit_Undef) subsumed++, removeClause(*cs[j]); else if (l != lit_Error){ deleted_literals++; if (!strengthenClause(*cs[j], ~l)) return false; // Did current candidate get deleted from cs? Then check candidate at index j again: if (var(l) == best) j--; } } } return true; }